Updated Fitness & Training Tool

Cardio Zone Calculator

Estimate your heart rate training zones using both the standard percentage-of-max method and the Karvonen heart rate reserve formula. Plan fat-burning, endurance and high-intensity cardio sessions with clear target ranges.

Standard Max HR Zones Karvonen HRR Zones 5 Training Zones Educational, Not Medical

Interactive Cardio Heart Rate Zone Calculator

Use this calculator to build a set of heart rate training zones for your cardio workouts. Start with the standard percentage-of-max approach, then switch to the Karvonen heart rate reserve mode if you know your resting heart rate and want more personalized zones.

If you enter a positive value here, it will be used instead of the formula estimate.

Standard zones are calculated as fixed percentages of maximum heart rate. This is simple and widely used, but still only an estimate. Always listen to your body and follow medical advice.

Measure your resting heart rate after several minutes of complete rest, ideally in the morning.

The Karvonen formula uses heart rate reserve (max minus resting) to personalize zones. This can better reflect fitness level than simple percent-of-max formulas, especially for trained athletes.

Heart rate training zones give you a framework for planning cardio workouts at different intensities. While exact boundaries vary between coaches and organizations, the five-zone model below is widely used in running, cycling and general fitness training.

Typical 5-Zone Heart Rate Model

Zone Intensity Approx. effort Typical session
Zone 1 Very light Easy conversation, warm-up / cool-down Active recovery, easy walking, very gentle cycling
Zone 2 Light / Endurance Comfortable but purposeful pace Long steady runs, base building, fat-burning cardio
Zone 3 Moderate Talking in short sentences Tempo segments, steady-state workouts
Zone 4 Hard Breathing heavy, speech limited to a few words Intervals, hill repeats, threshold efforts
Zone 5 Very hard Near-maximal, short bursts Short sprints, VO₂ max intervals

How to Use These Zones in Your Training

  • Build a base in Zone 2: Many endurance plans put a large share of weekly time in easy, sustainable Zone 2 sessions.
  • Add quality in Zones 3–4: Tempo and threshold workouts help improve speed at submaximal efforts.
  • Sprinkle in Zone 5: Short, controlled high-intensity intervals can develop power and VO₂ max.
  • Recover in Zone 1: Use very light sessions or complete rest to absorb training and avoid burnout.

Heart rate response can be affected by temperature, stress, caffeine, sleep, hydration and medications. Use these zones as flexible guides rather than strict rules, and always follow advice from your doctor or coach.

Cardio Zone Calculator – Plan Smarter Heart Rate Training

Heart rate training zones make it easier to match your workout intensity to your goals. Whether you are training for a race, improving general fitness or just trying to stay active safely, knowing your approximate zones can help you pace sessions and avoid overdoing it.

This Cardio Zone Calculator from MyTimeCalculator combines two popular approaches: a simple percentage-of-maximum method and the Karvonen heart rate reserve (HRR) method. Both rely on formulas and estimates, so results should be viewed as starting points rather than exact medical limits.

How the Standard Max Heart Rate Zones Work

In the standard method, your maximum heart rate is estimated from your age using a formula such as:

  • Classic: Max HR ≈ 220 − age
  • Tanaka: Max HR ≈ 208 − 0.7 × age

The calculator then defines zones as percentages of that maximum. For example, a common five-zone model is:

  • Zone 1 – 50–60% of max HR
  • Zone 2 – 60–70% of max HR
  • Zone 3 – 70–80% of max HR
  • Zone 4 – 80–90% of max HR
  • Zone 5 – 90–100% of max HR

This approach is easy to understand and widely used in group classes, fitness apps and basic training plans. However, it does not consider individual differences in resting heart rate or fitness level.

How the Karvonen Heart Rate Reserve Method Works

The Karvonen method uses heart rate reserve (HRR), which is the difference between your maximum and resting heart rate:

  • HRR = Max HR − Resting HR
  • Target HR = Resting HR + (% intensity × HRR)

Because it factors in resting heart rate, HRR-based zones can better match how exercise feels for trained versus untrained individuals. Two people with the same age and maximum heart rate can have very different resting heart rates and therefore different HRR values.

Inputs Explained

Both tabs in the calculator use a small set of simple inputs:

  • Age: Used to estimate maximum heart rate with either the 220 − age or Tanaka formula.
  • Max HR formula: Choose between classic or Tanaka; or override with a custom max if you have lab or field test data.
  • Custom max heart rate: Optional. If you have a clinically measured or reliably tested max heart rate, you can enter it directly.
  • Resting heart rate (Karvonen tab): Ideally measured in the morning after waking, before coffee, while you are calm and relaxed.
  • Decimal places: Controls how tightly the bpm values are rounded in the display.

What the Calculator Shows

After you click the calculate button, you will see:

  • Estimated max heart rate: Based on your chosen formula or custom value.
  • Heart rate reserve (Karvonen): The difference between max and resting heart rate.
  • Zone 1–5 ranges: Low and high bpm targets for each zone, ready to plug into your watch, fitness app or training plan.
  • Usage hints: A description of how each zone is typically used in cardio training.

Limitations and Safety Notes

Heart rate formulas are approximations. Some people have a true maximum heart rate much higher or lower than the formulas suggest. Medications, health conditions, stress and environment can also change how your heart responds to exercise on any given day.

  • This tool is not a medical device and does not diagnose or treat any condition.
  • People with heart disease, high blood pressure, chest pain, dizziness or other symptoms should get medical clearance before exercising vigorously.
  • If a workout feels too hard or unsafe at the suggested target, slow down or stop and seek medical advice.

Practical Tips for Using Heart Rate Zones

  • Start gradually: New exercisers may focus mostly on Zones 1–2 and add brief Zone 3–4 efforts later.
  • Use perceived exertion too: Combine heart rate with how you feel (breathing, ability to talk) instead of relying only on numbers.
  • Retest periodically: As fitness improves, resting heart rate may drop and max heart rate behavior can change slightly.
  • Adjust for hot days: Heart rate tends to rise in heat or humidity, so reduce target ranges if necessary and stay hydrated.

Other Fitness & Health Tools from MyTimeCalculator

Use these related calculators to plan your training and recovery:

Cardio Zone FAQs

Frequently Asked Questions About Heart Rate Training Zones

Understand how to use cardio zones safely and effectively in your workouts.

Standard max HR zones are simple and easy to remember, which makes them useful for group classes and general guidelines. Karvonen zones can be more personalized because they use your resting heart rate, but they also require more accurate measurements. Many people use both as cross-checks instead of choosing only one method.

If your fitness level or resting heart rate changes significantly, it can be helpful to recalculate your zones. Many athletes revisit their zones every few months or after a training block, especially if they see big improvements or changes in how workouts feel.

Some medications, such as beta-blockers, blunt the heart rate response to exercise and make standard formulas less accurate. If you take heart or blood pressure medications, ask your doctor or cardiac rehab team for specific guidance before relying on heart rate zones.

Brief spikes are common, especially during hills or sprints. If you feel fine and have medical clearance, easing back to your target pace is usually enough. If you feel dizzy, short of breath, have chest pain or feel unwell, stop exercising and seek medical attention immediately.